1. The Field of the Invention
The present invention relates to polyaxial screw systems that can be used for stabilizing adjacent vertebrae of the spine or other adjacent bones. The polyaxial screw system can be used with a rod clamp, plate, or other stabilizing structures.
2. The Relevant Technology
Polyaxial screws are commonly used in spinal operations for adjusting or stabilizing adjacent vertebrae. For example, in one conventional procedure a first polyaxial screw is screwed into a first vertebrae while a second polyaxial screw is screwed into an adjacent second vertebrae. A stabilizing rod is then secured between the polyaxial screws so as to fix the adjacent vertebrae relative to each other. Polyaxial screws can be positioned on each side of each vertebrae and can be positioned in any number of consecutive vertebrae with one or more rods extending between the different polyaxial screws.
One conventional polyaxial screw comprises a bone screw having a U-shaped collar pivotably mounted on the end thereof. The stabilizing rod is received within a U-shaped slot of the U-shaped collar and secured therein by a set screw being threaded into the U-shaped slot of the collar and biased against the rod. Although such systems are functional, they have certain drawbacks. For example, as a result of the collar being U-shaped, there is some risk that the collar will outwardly flare and thus fail as the set screw is threaded into the U-shaped slot and secured against the rod.
An additional problem with the above conventional polyaxial screw is that due to the specialized configuration of the U-shaped collar, the screw can only be used directly with a stabilizing rod. In some cases, based on the situation or surgeons preference, it may be desirable to use plates or other non-rod stabilizing structures to extend between the polyaxial screws. Accordingly, what is needed are polyaxial screw systems that overcome some or all of the above disadvantages.